Vacuum-type converter



W. T. BIRDSALL.

VACUUM TYPE CONVERTER.

APPLICATION FILED OCT. 9, 1915.

. 1,355,529. Patented Oct. 12,1920.

I WITNESSES: TIEIENTOR d 'd Q r; 66 3a. 3m.

UNITED STATES EN OFFICE.

WILFRED T. BIRDSALL. OF MONTCLAIR, NEW JERSEY, ASSIGNOR. BY MESNE ASSIGN- MENTS, TO WESTINGHOUSE LAMP COMPANY, A CORPORATION OF PENNSYLVANIA.

VACUUM-TYPE CONVERTER.

Specification of Letters Patent. Patnt d O t 12 1920 Application filed October 9, 1915. Serial No. 54,982.

To all whom it may com/awn:

Be it known that I, 'imuun) T. BumsaLL, a citizen of the United States, and a resident of Montclair, in the county of Essex and State of New Jersey, have invented a new and useful Improvement in Vacuum- Type Converters, of which the following is a specification.

My invention relates to vacuum type converters, and it has for its object to provide a device of the character described that shall be simple and inexpensive in manufacture and highly effective in operation, being especially free from short circuiting and allied phenomena.

The single figure of the accompanying drawing is a side view, partially in section and partially in elevation. of a converter embodying the preferred form of my invention.

In the operation of a vapor converter.- it is frequently desirable that the anodes be maintained at a high temperature for stability of operation and other reasons. If an anode attains a sufficiently high temperature, it emits negative electrons. and the flow of said electrons to another anode, which is, for the time being, positive in polarity, constitutes short oircuiting. Furthermore, even though the electrons emitted by an incandescent anode do not reach another anode, their presence in the arc path tends to repel the approach of current-carrying electrons from the cathode, resulting in irregular and undesirable action.

I have found also that if the well known negative flame, projected from the cathode and composed of vapor molecules, positive ions and electrons, impinges upon a hot anode, there is a tendency to break down said molecules. with the production of additional undesirable electrons.

For these and other reasons, it is desirable to provide means whereby the space immediately around a hot anode may be continuously swept free and clear from all electrons and from possible electron-forming molecules. By my invention, I provide the container of a vacuum-type converter with a condensing chamber or chambers, said condensing chambers being provided with comparatively narrow throats. and I mount the anodes of said converter at or near said throats, whereby a comparatively high vapor pressure is maintained over the surface of the cathode and there is set up a rapid current or blast of material from the cathode past the anodes and into the condensing chamber. I preferably return all condensed material from the cohdensing chambers to the cathode by special return tubes.

By exposing an anode-supporting stem or other cool, positively charged body Within the condenser chambers, means are provided for neutralizing the charge of any electrons whlch may be swept by the anodes.

By the use of my invention, I am enabled to operate both cathode and anodes at a much higher temperature than has been usual hitherto, with resultant higher operating reliability and a reduction in the size of the apparatus, because of the fact that the greater possibility of the presence of excess ionization, due to the high temperature, 1s more than compensated for by the conditions which prevent this ionization from becoming a source of trouble.

In a vacuum-type converter wherein electrodes of both polarities are maintained in an electron-emitting condition, as is the case when the anodes are operated at incandesccnce, bilateral conductivity will be present unless some means is provided for causing the are path itself to have unilateral conductivity. The current carriers in arcs are of three different forms comprising molecular masses, positive ions and electrons. any case, it will be found that the size of the positive carriers is, on the average, larger than that of the negative carriers. The result is that, if the positive carriers are too numerous, they will carry with them, be-

cause of collisions, more molecules of vapor and gas which may be in the path, than the negative carriers carry in the opposite direction. There results an accumulation of inert gases about the cathode. On the other hand, when conduction takes place almost entirely by electrons, there is an accumulation of residual gases about the anode. Under other conditions, when the positive ions and electrons are present in relatively proper amounts, the residual gases may diffuse more or less evenly throughout the are space.

It is evident from the above that, in general, in the presence of a residual gas, electric carriers move With more facility from cathode to anode than in the opposite direction on account of the difference in the size of the carriers and the differing numbers of collisions. In other words, the presence of a residual inert gas tends to promote unilateral conductivity in the arc path itself, independent of the unilateral arc conduction at the electrodes. If the molecules of the gas are moving toward the anode, the unilateral conductivity of the arc path will be accentuated. By employing a container of the character above described, wherein the location of the condensing chamber causes a rapid transfer of residual gas from the cathode to the anode, it will be seen that an appreciable rectifying effect may be developed within the arc path, evento such an extent that the unilateral conductivity of the electrodes themselves may be disregarded. I

Referring to the accompanying drawing for a more detailed understanding of my invention, I show the container of a vacuum type converter at 1, said container being preferably composed of glass or quartz. The container 1 is provided with anodes 2 and 3 composed of refractory material, such, for example, as iron, carbon or tungsten,

. and a vaporizable reconstructing cathode 4 composed of-mercury or suitable amalgams. A starting and keep-alive arc may be malntained to the cathode 4 by an auxiliary anode 5 of the usual type. The anodes 2 and 3 are mounted adjacent to restricted throats or passages 6 and 7 leading respectively to chambers 8 and 9. Said anodes are further provided with supporting stems 10 and 11, of abnormally large size, and said stems project entirely through the condensing chambers 8 and 9, for a purpose to be hereinafter pointed out. Condensed material accumulating within the chambers 8 and 9 is returned to the cathode through tubes 1212.

Having thus described the structure of a converter embodying my invention, the operation is as follows: upon starting a power are within the device from any suitable source, in accordance with ordinary converter practice, negative electrons, emitted from the cathode 4:, pass alternately to the anodes 2 and 3, and, if sufiicient current passes, said anodes are heated to incandescence. The throats 6 and 7 are so designed as to exert a pronounced throttling action, maintaining a much higher pressure over the-cathode 4 than extends in the chambers 8 and 9. As a result, there is a rapidly moving current of cathode vapor, residual gases and electronic material past the anodes into the condensing chambers and any negative electrons emitted by an incandescent anode will be prevented from passing to the other anode and causing a short circuit. Furthermore, a pronounced rectifying effect will be developed within the arc path itself, as above pointed out.

Throughout this description, I have explained the action of my device in accordance with the theory which seems most plausible in View of the present knowledge of the underlying phenomena. I desire it to be distinctly understood, however, that I do not confine myself to said theory of operation but merely present the same to aid in an understanding of the invention.

I claim as my invention 1. In a vacuum-type converter, the combination with a container provided with a condensing chamber having a narrow throat, of an anode mounted adjacent to said throat, and a cathode in said container, whereby, when said cathode is put in an active condition and an arc is established between said electrodes, a stream of vapor and electronic material will be caused to sweep past said anode into said condensing space and will serve to retard the movement of negative electrons from said anode to said cathode.

2. In a vacuum-type converter. the combination with a container provided with a plurality of condensing chambers, each of which is provided with a narrow throat, of an anode mounted adjacent to each of said throats, and a cathode within said container, whereby, when said cathode is put in an active condition and an arc is established between said cathode and said anodes, a current of Vapor and electronic material will be caused to sweep past each anode into the associated condensing space and the passage of negative electrons from one anode to the other will be prevented.

3, In a vacuum-type converter, the combination with a pair of electrodes, of means for maintaining an arc therebetween, and means for maintaining a unidirectional movement of all material in said are path, whereby said path will exhibit unilateral conductivity.

4. In mercury-vapor apparatus, the combination with a vaporizable cathode, of an anode mounted adjacent thereto, a restricted are path therebetween, a condensing chamber back of the anode and a drainage tube from the condensing chamber to the body of the cathode.

5. In a mercury-vapor device, the combination with a vaporizable cathode, of an anode mounted adjacent thereto, means providing such a restricted arc path therebetween that substantially all material in said away from said cathode, of means for accelerating said stream as it sweeps past said anode.

7. In an arc-type converter, the combination with a cathode, a plurality of anodes adapted to be successively energized to positive potentials, and means for establishing independent arc-streams originating from said cathode, impinging upon the several anodes during the times when they are positively charged, and sweeping past the latter in a direction away from said cathode, of means for accelerating said streams as they sweep past their'respective anodes.

8. In an arc-type converter, the combination with a cathode, a plurality of anodes adapted to be successively energized to posi tive potentials, and means for establishing independent arc-streams between each of said anodes and said cathode, of means for maintaining a unidirectional movement of all material in each of said arc paths, whereby said paths will exhibit unilateral-conductivity.

9. In an arc-type converter, the combination with a container provided with a main chamber and a plurality of condensing chambers opening into said main chamber, of a cathode within sa1d main chamber, an anode mounted wlthm each condensing chamber, means for establishing independent arc-streams through said openings between each of sa1d anodes and sa1d cathode,

and means for maintaining a unidirectional movement of all material in said openings.

10. In an arc-type converter, the combination with a container provided with a main chamber and a pluralit of condensing chambers opening into sa1d main chamber,

of a vaporizable cathode within said main chamber, an anode mounted within each condensing chamber, a drainage tube from the lower portion of each condensing chamher to the body of said cathode, means for establishing independent arc-streams through said openings between each of said anodes and said cathode, and means for maintaining a unidirectional movement of all material in said openings.

In testimony whereof, I have hereunto subscribed my name this twenty-ninth day of September, 1915.

W'ILFRED T. BIRDSALL. 

